Various machines include work implements that are raised and lowered to perform desired tasks. For example, skid steer loader machines may include a bucket that is raised and lowered to assist in transferring material between desired locations. In many cases, such work implements are coupled to a frame of a machine by a lift boom assembly that serves to control the movement of the work implement between the lowered and raised positions. Conventional lift boom assemblies include a boom directly coupled to a frame of the machine by a single pivot connection. This single pivot connection causes the work implement to travel along an arcuate path between the raised and lowered positions. In particular, when the boom starts to raise, there is forward movement of the work implement and, after the boom goes over center, there is a substantial amount of upward and rearward movement of the work implement. This lift path has the drawback of shortening the forward reach of the work implement when the boom is in the raised position.
Attempts have been made to overcome the drawbacks associated with boom assemblies having arcuate lift paths. For example, U.S. Pat. No. 5,542,814 issued to Ashcroft, et al. (“the '814 patent”), discloses a method of lifting a skid steer loader boom assembly along a generally “s”-shaped lift path. The “s”-shaped lift path is lifted in a generally vertical path until it reaches a first intermediate point, after which it is lifted along a path that inclines forward until it reaches a second intermediate point. Above the second intermediate point, the lift path travels along a generally vertical path until it reaches its maximum height. While the lift path provided by the disclosed boom assembly of the '814 patent seeks to improve over the lift path of the single pivot boom assembly, as illustrated in FIG. 3 of the '814 patent, the lift path may sacrifice machine stability for a more vertical path between the raised and lowered positions. In particular, at the second intermediate point in the lift path of the '814 patent, the bucket obtains its maximum forward reach, which is generally sustained until the bucket reaches its maximum height. With a loaded bucket in the region between the second intermediate point and the maximum height, the loaded machine center of gravity moves forward and increases the likelihood for the machine to tip over.
The present disclosure is directed to overcoming one or more of the problems set forth above.